1. Field of the Invention
The present invention relates to a framing device for stretching sheet materials and, more particularly, to an unique adjustable stretching frame for mounting canvas paintings.
2. The Prior Art
As is well known in the art, canvas paintings are conventionally mounted on wooden frames which are sometimes referred to as canvas frame stretchers. Known frames typically comprise wooden frame elements fastened together at the four corners with braces. The standard technique for stretching a canvas painting or other sheet material about a frame involves stapling a portion of the canvas to the edge of the frame and thereafter draping the canvas over the opposite side of the frame and manually stretching it about the frame. When the canvas is stretched to the required degree, it is stapled to the frame.
In recent years, a number of adjustable frames have also been disclosed with specific examples thereof being shown in U.S. Pat. Nos. 3,482,343 and 3,914,887. While a number of such frames are known in the art, they suffer from serious disadvantages and/or deficiencies. One disadvantage lies in the fact that known frames are very difficult to use and are expensive to manufacture. A further problem of presently known and/or commercially available framing devices is that they are not designed such that they may compensate for any expansion and/or contraction of the painting due to changes in temperature or humidity.
The above disadvantages of known frames is particularly acute when mounting very expensive canvas paintings or works of art. It may be briefly noted here that the mounting and/or restretching of an expensive canvas is a highly skilled art involving much expertise. For example, when dealing with a masterpiece, the tension placed on the canvas must be closely controlled. This tension will vary widely between paintings. Further, while known frames may have corners which are generally adjustable, they are adjustable only in one direction. Thus, the canvas must be removed along the entire side that is being restretched. Removing the canvas in this manner is a significant problem inasmuch as it is essential, with valuable works of art, that they not be touched even by the tip of one's finger. Fingerprints lead to the cracking and deterioration of the painting.
A further problem facing this art is the deterioration of a canvas painting with age. While the precise theory, or underlying cause, for the deterioration is not fully known, it has been found that canvas paintings will deteriorate at the point of contact of the painting with the canvas. This deterioration is typically along the front outer edges of the frame. It is believed that this damage is due to the reaction of the oils or paint with the material (i.e., wood) of the frame itself. As a further point with regard to known stretching apparatus or frames, in stretching a canvas, it is important that the tension exerted between the frame and the canvas be adjustable in order to prevent premature damage to the canvas. This operation requires a great amount of tension to maintain the canvas in a taut condition over the frame. It is also highly desirable, when stretching or restretching certain canvas paintings, (especially those that are aged) to stretch them at different tensions along different portions of the canvas. This is frequently necessary after the canvas has been mounted for a number of years and certain portions of the canvas have become loosened or stretched. With existing frames, it is not possible to retighten or restretch the canvas without removing the canvas from the frame. The present invention relates to an apparatus that overcomes the above noted deficiencies of known devices.